7 Symptoms Of Bad Bellows That You Need To Look Out For – Indicate Your Bellows Have Gone Bad

symptoms of bad bellows

If you have a boat, then you know that bellows are an important part of the vessel. But what exactly are they? Bellows are actually a type of pump that is used to move air or water. They are often used in boats to help pump out bilge water.

There are many different types of bellows, but they all work in basically the same way. The air or water is drawn into the chamber of the bellows and then forced out by the action of the piston.

One of the most common problems with bellows is that they can become clogged with debris over time. This can cause them to lose their ability to effectively pump out bilge water. If you notice that your boat is taking on more water than usual, it’s a good idea to check your bellows for blockages.

Another problem that can occur is leaks. Over time, the seals on bellows can wear out and allow air or water to escape. This can obviously lead to big problems if not fixed in a timely manner.

Boat Out-Drive Bellows when they fail

What are some of the symptoms of bad bellows?

The primary symptom of bad bellows is water leakage. Bad bellows can also stop your engine from working smoothly. Other than that, your boat may sink a little after staying docked for hours. Bad bellows can also cause loud noises, rusting, overheating, dry rotting, etc.

Anyways, that was a summarization of multiple symptoms lumped together. Obviously, that may not be enough for many of you. That’s why we’ve listed the symptoms and had them simplified for you.

How to inspect your bellows


The bellows on your boat play an important role in keeping water out of the engine. Over time, they can become damaged or worn, causing leaks. It’s important to inspect them regularly and replace them if necessary. Here’s how to do it:

  • 1. Start by visually inspecting the bellows for any cracks, tears, or other damage. If you see any, it’s time to replace them.
  • 2. Next, check the clamps that hold the bellows in place. Make sure they’re tight and not corroded.
  • 3. Finally, use a pressure gauge to test the integrity of the bellows. If they’re not holding up to pressure, they need to be replaced.

Do Bad Bellows Possess Threats Towards Your Boat?

Before we jump to the main discussion, let’s talk about the bellows first. Bellows are often overlooked despite being extremely vital. Understanding the importance of a component can change your perspective about a matter. For instance, to prevent problems with Stratos boats, you’ll need basic knowledge about it.

Bellows are gaskets that keep water from entering the boat engine. This alone makes bellows a super important component. You can say bellows act like protection to your boat engine. There are many advantages and disadvantages of bellows. But there’s one thing that people often wonder, can bad bellows sink a boat?

Yes, bad bellows can potentially sink a boat. In fact, Boat US, an association for boat owners claim bellows can sink a boat. They’re the 2nd most prominent reason behind boats sinking at the dock. Bad bellows create water intrusion. When too much water comes in, the boat can sink.

As you can see, the bellows are super important for your boat’s safety. By knowing the symptoms of bad bellows, you can avoid dire circumstances.

7 Signs That Indicate Your Bellows Have Gone Bad

In the previous segment, we’ve mentioned how bad bellows on boats can create problems. While you can’t stop a bellow from going bad but you can save your boat. Being aware of symptoms is helpful and always gives you an edge. It’s easy to deal with outboards by knowing the symptoms of bad trigger outboards.

That’s why we recommend you go through all the symptoms one by one. By doing that, you can easily avoid a potential disaster. On top of that, the only fix for bad bellows is to replace them. If you detect any of these symptoms in your boat bellows, replace them immediately.

Symptom 1: Bad Bellows Cause Water Leakage

We have already talked about this earlier in the discussion. But this time let us show you how you can easily guess the bellows are bad. To know whether your bellows are good, simply pull out the hatch. After pulling the hatch out, you may see water in the bilge.

This can happen due to many reasons. For instance, the bow wall of the bilge can be cracked. That’s why you will have to rule the possibility out by yourself. For this, you’ll have to clean the bilge first. After that, take the boat to the open water and reopen the engine hatch.

If you see water again, this is possibly due to the bad bellows. If that happens, the only option is to replace the bellows. To help you out, we’ve had our experts recommend their best picks- You can pick whichever fits in your boat and get started!

Symptoms 2: Bad Bellows Can Interrupt the Engine

Stern Drive Repairs Part

Other than water leakage, you should look out for your engines. Because bad bellows can interrupt the engine’s functions. You may notice that your boat engine is hesitating when starting. You can also find out that it requires a harder start than usual.

If you see any kind of unusual engine noises, it can be due to bellows.

Symptom 3: Bad Bellows Can Cause Loud Noises

The loud noise issue is primarily a U-joint issue. If the bellows have gone bad, you might hear loud noises. These noises usually come from the back. To test this symptom, take the boat to the water. After that, try turning the boat. If the U-joint bellows have gone bad, you’ll hear louder noises. Simply replace the U-joint bellows to get out of this problem.

Symptom 4: Engines Can Overheat Due to Bad Bellows

Like water leakage, noises and bad engine starts, overheating is also a common issue. We’ve already discussed that bad bellows can cause water insertion. If the water has entered, it will interrupt your engine’s cooling system. And when that happens, the engine will start overheating. That’s why overheating of the engine is a great sign that you shouldn’t ignore.

Symptom 5: Bad Bellows Can Make Your Boat Sink

This is one of the major signs that your bellows may have gone bad. After docking the boat, it’s possible for your boat to sink. It wouldn’t totally sink under the water obviously. But you’ll notice that the boat isn’t completely floating. It’s actually a couple of inches down in the water.

When that happens, you’ll see that water has seeped through the cracks. The bilge will be collecting water. And that happens due to bad bellows. You can easily locate the bilge pump on the boat. Simply check it and see whether it’s fine or not.

If you notice anything like this, immediately replace the bellows.

Symptom 6: Bad Bellows Can Cause Rusting & Dry Rotting

Bad bellows to allow water into the engine. That’s why looking for rust signs or dry rotting signs is a smart idea. Open up the engine and look for the bearings. If the water has contacted the bearing grease, there will rust around. And that’s a good way to tell that you have bad bellows. Other than that, dry rotting is also a great sign.

Symptom 7: Bad Exhaust Bellows Creates Unpleasant Odor

This symptom is more associated with the exhaust bellows. An unpleasant smell coming out from the engine indicates a strong bad exhaust bellows symptoms. If the exhaust bellows are bad, it will cause water to get in the exhausts. The fuel then gets mixed with the water. This fuel then burns and spreads a bad smell.

Simply replace the exhaust bellows and you’re all great. These were some of the important symptoms that you should look out for. Overall, you can always avoid bad bellows problems by maintaining your boat properly.


How often should bellows be replaced?

Bellows should be replaced about every two years or so. It’s because they’re extremely important and they’re the ones who prevent water leakage. You should also inspect the bellows regularly and look for cracks. Bad bellows can destroy your boat engine over time by allowing water.

How long does it take to replace the bellows?

Replacing the bellows only takes 30 minutes or less. They’re fairly easy to remove and reinstall. The optimal time to replace the bellows is after a long session. Because then you’ll be able to tell that the bellows have gone bad. If there’s water inside the engine, it’s time to replace the bellows.

What can I use for bellows adhesive?

There are many bellows adhesives available online that you can use. These adhesives are resistant to oil, grease, and water. Because of that water, oil and grease can’t loosen the seals of the exhaust or u-joint bellows. They’re also fairly cheap on websites like Amazon and easy to apply.

What is the range of bellows?

A bellows pressure gauge is recommended for control pressure ranges between 0.2 to 1 kg/cm2 (2.8 to 14.5 psi).

What material is used for bellows?

Bellows are typically made of metal alloys such as brass, bronze, nickel, and stainless steel. They are designed to provide a flexible connection between the engine and exhaust system and are typically impregnated with a pesticide to prevent corrosion. Additionally, some boats may have a bellows around the rudder or propeller shaft.

Take Away

That was everything we could explain and deliver on symptoms of bad bellows. We hope that these symptoms have given you some insights about the bellows problems. Also, check whether the exhaust pipe comes out of your boat or not. The pipe will hang downward and that implies possible damage to the exhaust bellows.

Finally, have a nice day.

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